Accumulator



Dec. 4, 1962* w. H. PEET 3,066,699

ACCUMULATOR Filed Dec. 10, I958 2 Sheets-Sheet 2 F'IG-3- ATTORN YS United States Patent Ofilice Patented Dec. 4, 1962 3,066,699 ACCUMULATOR William Harold Feet, 1607 Firndale Place, Ann Arbor, Mich. Filed Doc. to, 1958, Ser. No. 779,3o7 11 Qlairns. (Cl. 138-30) The present invention deals with an improved accumulator to function as an energy storing device for hydraulic systems.

It is a general object of the invention to provide an improved accumulator which is of very simple and inexpensive construction, featuring a sheet-like flexible diaphragm of fluid impermeable material serving to subdi 'vide a pressure easing into fluid pressure spaces or chambers on the opposite sides of the diaphragm. One of these spaces is a liquid pressure compartment or chamher into and out of which the hydraulic liquid of the system is respectively received and expelled under pressure when required. The other space is a gas compartment or chamber charged with a suitable gas under pressure to act as the energy storage medium which is separated from the hydraulic liquid by the flexible diaphragm.

A further object is to provide an accumulator which, by reason of the improved character of its flexible diaphragm and associated provisions, may be operated at 100% displacement of either its gas or liquid compartment, thus providing an extremely high volumetric capacity in relation to the size of the device.

It is another object to provide an accumulator having a casing provided with improved means to protect the diaphragm, in being flexed under pneumatic and hydraulic pressures, against extrusion and damage. This is accomplished by providing for a controlled flexure of the diaphragm.

It is another object of the invention to provide an accumulator of simple character, as described, in which means are provided, for the aforesaid purpose of diaphragm flexure control, in one of several different embodiments, but in which the purpose common to all is to prevent extrusion of the material of the flexed diaphragm. In a preferred embodiment of the invention, the anti-extrusion control function is performed by a liplike element internally of the accumulator casing engaging and sustaining the flexed diaphragm to prevent the material of the latter against entry into any corner or restricted zone likely to occasion extrusion. In accordance with a still further preferred concept, this sustaining element is in the form of an integral lip, or a separately fabricated lip suitably attached, on one of two generally similar casing members controlling a liquid flow port or passage through the latter to the liquid pressure space.

Yet another object is to provide, in this preferred embodiment of the invention, a sealing lip as described which is tapered or feathered toward a free terminal lip edge sustaining the flexed diaphragm adjacent the wall of a casing member. The feathered lip edge provides no space into which the material of the diaphragm might be extruded with subsequent damage.

A still further object is to provide an accumulator whose casing is fabricated of two similar parts of rounded end, generical semi-cylindrical cross-section with improved provision to band and sealingly secure these parts together.

A still further object is to provide a lip-type accumulator arrangement, as described in the preceding paragraph, in which the accumulator casing is formed by two generally similar rigid casing members, one having a feathered lip of the sort described formed along meeting edge zones of the two parts; and in which the sheet-like flexible diaphragm is marginally clamped between these zones.

In accordance with another embodiment, it is an object to provide an accumulator having a flexible diaphragm supporting element as described which is formed of material slitted and offset inwardly from the wall of the easing member which defines the liquid pressure space or chamber. This element is engageable by the pressureflexed diaphragm.

In any of these forms controlled bending of the flexible diaphragm is insured, thus preventing sharp creases and rapid destruction due to high stress concentration, such as would otherwise result.

A still further object of the invention is to provide an accumulator structure in accordance with any of the above mentioned embodiments, in which the gas pressure space or chamber of the accumulator casing is chargeable with pressure air or other gas through a normally plugged charging port or opening, in the manner illustrated and described in my copending application, Serial No. 753,521, filed August 6, 1958 and now abandoned, and also in a continuation of that application, Serial No. 143,025, filed October 2, 1961 and now Patent No. 3,020,928.

The foregoing as well as other objects will become more apparent as this description proceeds, especially when considered in connection with the accompanying drawings, illustrating preferred embodiments of the invention, wherein:

FIG. 1 is a fragmentary side elevational view, partially broken away and in axial section, illustrating an accumulator in accordance with the preferred embodiment of the invention, different flexed positions of the diaphragm thereof being respectively shown in dotted and dot-dash line;

FIG. 2 is a view in transverse vertical section along line 2-2 of FIG. 1, a flexed position of the diaphragm as controlled by a sustaining lip being indicated in dotted line;

FIG. 2A is a fragmentary view in section similar to FIG. 2, showing an alternative form of casing construction to provide a sustaining lip of the sort describe FIG. 3 is a fragmentary view in longitudinal vertical section through an accumulator in accordance With a modified embodiment of the invention;

FIG. 4 is a View in transverse vertical section on line 4-4 of FIG. 3, flexed positions of the diaphragm being shown in dotted line; and

Referring first to FIGS. 1 and 2 of the drawings, the reference numeral it generally designates a fluid energy storage accumulator in accordance with a preferred embodiment of the invention. This accumulator comprises a casing 11 of cylindrical cross sectional outline having its opposite ends in a semi-spherical outline. The casing is formed of a pair of generally similar casing members 12, 13, each of generally semi-cylindrical cross section, disposed with their concavitie-s in mutually facing relation to one another, and with meeting edge portions or zones 14 thereof specially formed (as will be described) and in s9 ransverse register. The casing members 12, 13 are preferably formed of steel or other rigid metal, one thereof, i.e., the uppermost member 12 appearing in FIGS. 1 and 2, being provided with one or more liquid inlets and re turn flow ports 15 in its wall, adjacent its specially formed edge portion or zone 14. It is to be understood that this edge formation 14, which serves to prevent both creasing of the diaphragm and its extrusion, extends substantially continuously around the margin of the casing member 12.

The other casing member 13 is, as appears in FIG. 2, of like cross sectional outline, and its specially formed edge portion or zone is designated 16.

With the casing members 12, 13 disposed in the opposed, mutually facing relationship shown in FIG. 2, they fixedly clamp therebetween an enlarged bead 17 formed along the peripheral marginal edge of a sheet-like flexible diaphragm 18 of fluid-impermeable material, the trans verse width of which diaphragm substantially exceeds the diameter of the casing 11. It is to be understood that the diaphragm margin is continuously clamped in this fashion about its entire periphery. The casing members 12, 13 are held in diaphragm clamping position by means of a metal band 19 shaped in cross section to conform with the cylin- 'drical outline of the casing 11 through its periphery and its semi-spherical end outlines. The band 19 is suitably applied in fluid-tight relation to the casing members and diaphragm clamped therebetween. As illustrated in FIG. 2, it is provided with one or more radial tubular fittings 20 for the inflow and outflow of liquid to and from liquid pressure port 15. Furthermore, the lower casing member 13 is preferably provided with a device 21 for charging the interior of the casing beneath the diaphragm (FIG. 2) with air or other pressure gas. The device 21 may be of the type illustrated and described in my copending application, Serial No. 753,521, identified above, comprising a short radial fitting sleeve 22 welded in an opening in the band 19 in radial communication with a passageway 23 in the wall of member 13, which opening is occupied by a sealing plug 24 of rubber or the like. A retaining disk 25 is threaded into the sleeve 22 to hold plug 24 in place against internal gas pressure in the space of chamber beneath diaphragm 1%, this disk having a central aperture through which a filling hypodermic needle or like instrument may be inserted to pierce and penetrate the plug 24, and the disk being held in place by a removable closure plug 27. Plug 27 is provided with a conical nose 26 seating in the aperture of disk 25 to prevent outward cold flow of the material of rubber plug 24. The peripheral location of this charging means with relation to the casing 11 is not necessarily fixed, and may be other than as shown.

The special edge portions or zones 14, 16 of t re respective casing members 12, 13 are similarly formed to provide a return bent or re-entrant lip, designated 29' in each instance. These lips are only very slightly flexible under pressure exerted thereon by the diaphragm 1S, and the lips are tapered to a feather edge portion 30. These edges are positioned along the closely adjacent internal wall of one or the other of the casing members 12, 13, thereby preventing creasing and/ or extrusion of the material of the diaphragm, in flexing, as against a sharp edge or against the opening 15 or passage 23.

In the normal position of the edge zone formation 14 of the upper, liquid pressure chamber member 12, its lip edge 30 is spaced, say, 0.010 inch from the casing wall, while the spacing of the corresponding lip edge 3t) of the air pressure chamber member 13 may be greater. However, complete closure of the passage between the edge of the lip and the casing wall does not take place.

In use, with the space 32 in casing 11 charged with air or other gas at a desired super-atmospheric pressure, and with a liquid line connected to liquid inflow and return fitting 20, the diaphragm 18 as subjected to air pressure from beneath will bend and assume, for example, the upwardly flexed contour indicated in dotted line in FIGS.

1 and 2, and may flex the feathered lip 29 outwardly somewhat toward the Wall of casing member 12. A reverse flow of liquid through fitting 2d and port 15 may cause this lip 29 to flex inwardly at least to its solid line position of FIG. 2. Liquid will thus flow between the casing wall and feathered lip edge 31? and into the upper liquid pressure space of chamber 34 above diaphragm 18, and will be forced to recede from that space by the pneumatically pressurized diaphragm in a manner characteristic of the operation of accumulators of this type. Should the chamber 34 become filled with liquid to force diaphragm 1d well into air pressure chamber 32, the lip formation 29 of the lower casing member 13 will protect the diaphragm against creasing and/or extrusion, in the same manner as the member of the upper chamber.

Thus, in reference to either the liquid pressure space or chamber 34 or the air pressure space 32, the feathered lip edges 39, as pressed by the diaphragm, prevent extrusion of the material of the latter such as might damage or weaken it. There is no abrupt corner in this zone to be contacted or entered into by the diaphragm. Both feathered lip formations enable the fluid to easily bypass the same in entering or leaving the casing 11.

It should also be noted that the well rounded outline of the edge. formations 14 and 16 permits controlled bending of the diaphragm and thus prevents high stress concentration on the flexible membrane. This feature is conducive to long life and resists fatigue of the diaphragm material.

FIG. 2A illustrates an alternative form of casing and diaphragm controlling lip construction. Here, a lip formation 14 is shown as constituted of a length of lip material, formed in the cross sectional outline indicated above as desired. It is secured, as by induction welding at 14", to the inner wall of the casing, designated 11', prior to insertion of the diaphragm 18', and the edge of the latter is clamped between the formation 14' and the corresponding formation 16' of the lower portion of the casing. In this embodiment the edge of the casing 11 to which formation 14' is secured is overlapped on its bottom half, and the provisions for clamping the opposite side of the diaphragm may be similar, or may be as hereinafter described in connection with FIGS. 3 and 4. In other respects, the construction is the same as in FIGS. 1 and 3, and corresponding reference numerals, primed, designate corresponding parts.

The alternative embodiment of the invention illustrated in FIGS. 3 and 4 employs a casing generally designated 36 which may be of one-piece construction, with a continuous crimped formation 37 therearound by which the continuous peripheral bead 17 of the flexible sheet-like diaphragm 18 is clamped in a fluid tight way. In units handling higher pressures elongated reinforcing bands 37' may be welded along the top and bottom of the formation 37 to brace it relative to the casing wall. The diaphragm thus subdivides casing 36 to provide a liquid pressure space 38 and an air pressure space 39 respectively above and beneath diaphragm 18. The wall of the casing 36 is preferably equipped with a hypodermic gas filling device 21 of the sort shown in FIG. 2. i

Along the upper central Zone of the casing 36, the latter is provided with a pair of longitudinally extending slits 49 in transversely spaced, parallel relation to one another, and between these slits the material of the casing 36, represented by an elongated strip or reed 41, is offset radially inwardly. The slits 40 are preferably formed by running a V-shaped milling cutter longitudinally along the exterior surface of the casing member, resulting in the formation of the chamfered longitudinal edges 41 on the reed 41. When thus formed and offset, the reed 41 exposes a liquid inflow and return port or opening 42 of elongated outline, the strip 41 remaining integrally connected to the wall of the casing 36 at its ends, as shown in FIG. 3. One or more retainer or stop straps 43 are welded to the exterior of the casing across the port or opening 42, for the purpose of limiting upward movement of the reed 41; and an elongated liquid manifold 44 is marginally welded along the top of the casing, enclosing the area or zone of the port 42. This manifold is equipped with one or more liquid flow fittings 45 opening through an aperture 46 in the manifold.

I In use, as initially pressurized by air in chamber 39, the diaphragm 18 is flexed upwardly into engagement with the reed 41, urging the same upwardly as indicated in dotted line toward a position adjacent or in the opening of port 42 to the liquid pressure chamber 33. Upon a reverse flow of pressure liquid communicated through fitting 45 to manifold 44, the reed 41 is flexed inwardly and the chamber 38 is filled with liquid until the charge shall have reached its maximum by reason of a pressure limiting device exterior to the accumulator (not shown).

It is seen that the invention affords an improvement in accumulators in which, regardless of whether one or another type of flexible diaphragm control element is employed, or its equivalent, it is impossible for the valve actuating flexible diaphragm to extrude into any sharp corner and possibly damage itself. All units are extremely simple and inexpensively manufactured and assembled, characteristically by reason of their use of a simple flat, sheet-like diaphragm marginally clamped in a leak-proof fashion between continuous peripheral formations of a diaphragm casing, whether the latter is formed as shown in FIGS. 1 and 2, or as shown in FIGS. 3 and 4. The accumulator, in any embodiment thereof, is adapted for application in any type of liquid handling line simply by the connection of its liquid port fitting to an appropriate liquid pressure line of the system.

In any of the adaptations of FIGS. 1 through 4, the common characteristic of the flexible sheet-like diaphragm enables the accumulator to be operated at either 100% displacement of either its gas chamber or compartment or its liquid pressure chamber, thus providing an extremely high volumetric capacity, indeed, in relation to the cubicle occupancy of the device. In this respect, the improved accumulator has a great advantage over heretofore proposed flexible separator type, bladder or diaphragm accumulator constructions, in which any attempt to exceed a very limited displacement inevitably results in failure of the flexible separator.

What I claim as my invention is:

1. An accumulator comprising a hollow casing having a flexible diaphragm secured therein to provide fluid receiving chambers on opposite sides of said diaphragm, said casing having a wall cooperating in the definition of one of said chambers provided with a port adapted to communicate said one chamber with the exterior of said casing, and a flexible leaf connected at one end only to the interior of said casing overlying said port and presenting an edge at the opposite end thereof normally spaced inwardly from said casing wall to open said port to said one chamber, the other of said chambers being adapted to contain a fluid under pressure acting on said diaphragm to urge the same toward said one wall of said casing and into engagement with said leaf to flex the same outwardly toward said casing Wall to a limiting position wherein said edge thereof is substantially flush with said casing Wall to substantially close the space between said edge and casing wall, thereby precluding outward extrusion of said diaphragm through said space, said leaf in said limiting position smoothly merging at said edge with said casing wall to uniformly support said diaphragm without sharp bends.

2. An accumulator comprising a hollow casing having a flexible diaphragm secured therein to provide fluid receiving chambers on opposite sides of said diaphragm, a leaf in one chamber connected at one end to said casing, said leaf having a portion extending from its connected end inwardly with respect to said casing in overlying relation to the margin of said diaphragm, said leaf at the inner extremity of its overlying port-ion curving away 6 from said diaphragm in an arc and terminating in an edge merging smoothly with the inner surface of the case to uniformly support the diaphragm when collapsed without sharp bends.

3. The accumulator defined in claim 2 wherein the edge of said leaf is normally spaced inwardly from said casing, and wherein said leaf is flexible for outward flexure by said'diaphragm to a limiting position wherein said edge thereof substantially closes the space between said edge and said casing, thereby precluding outward extrusion of said diaphragm through said space.

4. The accumulator defined in claim 2 wherein said casing is provided with a port located to communicate said one chamber with the exterior of the casing, said leaf extending over said port and the edge thereof normally being slightly spaced inwardly from said casing to open said port to said one chamber, said leaf being flexible for outward flexure by said diaphragm to a limiting position wherein said edge thereof substantially closes the space between said edge and said casing, thereby precluding outward extrusion of said diaphragm through said space.

5. An accumulator comprising a hollow casing having a flexible diaphragm within and extending across said casing, means for marginally clamping and sealing said diaphragm to divide said casing into fluid receiving chambers on opposite sides of said diaphragm, said means including leaves respectively extending along the margin of said diaphragm on opposite sides thereof, said leaves being connected to said casing at their adjacent ends and extending inwardly therefrom with respect to said casing to provide opposed portions gripping and sealing the margin of said diaphragm, said leaves at the inner extremities of said opposed portions each curving away from the other in an arc and terminating in an edge merging smoothly with the inner surface of said casing to uniformly support said diaphragm when collapsed without sharp bends.

6. The accumulator defined in claim 5 wherein said casing is provided with ports on opposite sides of said diaphragm to communicate said chambers with the exterior of said casing, said leaves extending over said ports and the edges thereof normally being slightly spaced inwardly from said casing to open said ports to said chambers, each leaf being flexible for outward flexure by said diaphragm to a limiting position wherein said edge thereof substantially closes the space between. said edge and said casing, thereby precluding outward extrusion of said diaphragm through said space.

7. The accumulator defined in claim 5 wherein the wall of said casim on one side of said diaphragm has an extension overlapping the wall thereof on the opposite side of said diaphragm, and wherein one of said leaves is integral with said overlapped wall.

8. The accumulator defined in claim 5 wherein said casing is formed of separate sections the margins of which approach one another and have said leaves as integral portions thereof, and means for securing said casing sections together.

9. The accumulator defined in claim 8 wherein said securing means comprises a band encircling said casing externally along the margins of the sections thereof.

10. An accumulator comprising a hollow casing having a flexible diaphragm secured therein to provide fluid receiving chambers on opposite sides of said diaphragm, said casing having a wall cooperating in the definition of one of said chambers provided with a port adapted to communicate said one chamber with the exterior of said casing, and a flexible leaf connected at one end to the interior of said casing overlying said port and presenting an edge normally spaced inwardly from said casing wall to open said port to said one chamber, the other of said chambers being adapted to contain a fluid under pressure acting on said diaphragm to urge the same toward said one wall of said casing and into engagement with aeeaeeo said leaf to flex the same outwardly toward said casing wall to a limiting position wherein said edge thereof is substantially flush with said casing Wall to substantially close the space between said edge and easing Wall, thereby precluding outward extrusion of said diaphragm through said space, said leaf in said limiting position smoothly merging at said edge with said casing wall to uniformly support said diaphragm without sharp bends.

11. The acclumulator defined in claim 10, wherein said said leaf References fitted in the file of this patent UNITED STATES PATENTS Herman July 20, 1943 Mitchell Oct. 20, 1953 Mercier July 30, 1957 

